Prior art implantable devices have typically been powered by utilizing a permanent power source (e.g. battery) or by receiving power directly (e.g. wireless link) via an externally located device. Inclusion of a replenishable power sources (e.g. rechargeable battery) located within the implantable device is becoming commonplace. These power sources can be recharged during a recharging session via a direct electrical connection to an external device or via a wireless link. However, it is more practical to use a wireless link. Charging of the power source via wireless link typically occurs through the transmission and reception of an RF signal from the external device to the implantable device. One prior art system is that described in U.S. Pat. No. 6,381,496, which is incorporated herein by reference. Such charging sessions generally take from one to several hours to fully recharge the battery.
Typically, the implantable device includes another communications transceiver for communication with an external programming device. The external programming device functions to allow the patient or other person to program/control the operating characteristics of the implantable device. During the recharging session, the RF recharging energy is substantial and may interfere with the other communications between the implantable device and the external programming device. In addition, it is desirable to monitor the status of the charging operation and implantable device during the charging session. Errors or problems with the battery charging could pose significant safety issues and may require explanting of the device.
Accordingly, there is a need for an implantable device, external charging device, and wireless communication technique that will allow for communications from the implantable device during a recharging session and minimize any errors in such communications. Moreover, there is needed an implantable device, external charging device and communication technique that utilizes the wireless RF charging communications link as the means for communication.